The invention concerns a microwave generating device for the treatment of workpieces with at least one microwave antenna connected to a microwave source, the antenna having an elongated conductor for the production of alternating electromagnetic fields, with a housing forming a cavity resonator and with an output region for the microwaves located in a widening portion of the housing substantially in a focus region of the housing resulting from that widening, wherein an at least non-diverging housing region adjoins the widening portion of the housing.
WO 96/23318 (corresponds to DE 195 07 077 C1) discloses a plasma reactor categorizing the invention which comprises a rotationally symmetrical cavity in the form of an ellipsoidal resonator. The free end of a coupling pin is disposed at a first focusing point while a second focusing point of the ellipsoidal resonator is surrounded by a quartz cap thereby forming a plasma treatment region about that focusing point. Disadvantageously, the treatment region is small and concentrated only radially about the focusing point.
DE 195 03 205 C1 discloses a device for producing plasma in an underpressure container by means of alternating electromagnetic fields, wherein a rod-shaped conductor is guided, within a pipe of insulating material, through the underpressure container. The inner diameter of the pipe is larger than the diameter of the conductor and the pipe is filled with gas to prevent plasma from being generated therein. Plasma is produced in the direct surroundings of the pipe, since the rays are most intense at that location. The influence of the high energy input on the pipe, the change of the radiation due to impurities and the danger of forming a coating about the pipe are all disadvantages of this procedure.
DE 39 23 390 A1 discloses a device for generating a large area evaporated film using at least two separated activated gases. Towards this end, two microwave conducting cavities, each having its associated microwave generator, are disposed parallel to two opposite sides of a substantially rectangular housing. Rod antennas extend from the microwave generator in an alternating manner and at right angles to the extension of the conducting cavities, which are likewise parallel to each other, which penetrate into the housing, and which end and are terminated within the housing at the corresponding sides facing away from the respective conducting cavity. Standing microwaves of differing intensities are formed along the antennas. A certain degree of homogeneity is attained through the parallel configuration of the antennas and the staggered feeding thereof on opposite sides. This configuration is structurally demanding and therefore expensive.
It is the underlying purpose of the invention to further improve a device of this kind for the production of microwaves, in particular, for the continuous treatment of large workpieces.